In the past, mushroom compost has been prepared by initially mixing the ingredients together, then periodically turning over the mixture for purposes of aeration as the microorganisms in the mixture develop, and then flowing hot steam through the mixture to kill or deter the further development of certain types of bacteria and other organisms. Several variations of this process have been used, but in all cases the compost is treated in relatively small quantities or batches, and it has been extremely difficult to provide a standard pasteurized compost from one batch to another.
Attempts have been made to pasteurize in bulk large quantities of the mushroom compost, but for one reason or another such attempts have not been entirely successful. It is apparent that unless the entire mass of compost material is treated in essentially the same manner, the quality of the compost will vary from place to place within the mass. Where, for example, the compost mass is exposed to the atmosphere, the exposed surface material may become contaminated and eventually contaminate the entire batch. If on the other hand, a room is filled with the compost, those portions of the compost contacting the walls of the room are cooler than the rest of the mass and water condenses thereon making the adjacent portion of the compost undesirably moist. Moreover, air will not circulate through the portions of the compost mass in proximity to the walls and floor of the room wherefor the aerobic thermofils therein do not develop properly while an unwanted development of the anaerabic thermofils occurs.
Irrespective of the failures which have heretofore resulted from attempts to pasteurize in bulk large quantities of mushroom compost, I have found that bulk pasteurization is, nevertheless, the best way to produce economically mushroom compost of consistantly high quality and uniform composition. By carefully controlling the temperature and moisture content of the entire compost mixture while at the same time continuously aerating the mixture it is possible to enhance the growth of desirable aerobic organisms while discouraging the growth of undesirable anaerobic and other organisms.